Shoulder Harness Redux

Surprisingly, given the sudden stops that were likely to occur in a ditching or carrier-landing arrestment (not to mention being stopped by the barrier), U.S. Navy carrier airplane seats did not have shoulder harnesses before mid 1942.

It may be that ditchings and crashes in the years between the world wars may have been relatively rare, although a black eye, missing teeth, or a scar on a naval aviator's forehead from encountering his gun sight or instrument panel was not unusual. Shoulder harness were also thought by the Bureau of Aeronautics (BuAer) to impede escape in the event of a crash or perhaps considered by the pilots to be a nuisance in using the early gun sight or the plotting board that slid out of the instrument panel, which required leaning forward. (The U.S. Army also did not adopt shoulder harnesses before the war but the Brits did.)

Nevertheless, the benefit of an upper body restraint began to be recognized in the fleet in early 1942. In John B. Lunstrom's excellent The First Team: Pacific Naval Air Combat from Pearl Harbor to Midway, he wrote that VF-42's Walt Hass, after he had ditched a Grumman F4F Wildcat in March 1942 for the second time, designed a "special harness" to keep his face away from the gunsight in the event of another. (The squadron also requested that BuAer provide shoulder harnesses, which were not forthcoming at the time.) It's probably unit-level initiatives that resulted in reports that some F4Fs had shoulder harnesses at the battle of Midway in early June 1942. Dick Best reportedly stated that the new SBD-3s delivered to VB-3 in May 1942 had shoulder harnesses.

Jim Maas, who is the subject matter expert for the Brewster F2A Buffalo, reports that a BuAer change order to install shoulder harnesses in it was issued on 12 June 1942, to be accomplished "as soon as practicable" but no later than the next major overhaul. According to the January 1948 issue of Flying Magazine, the requirement to modify F4Fs to add shoulder harnesses was issued on 18 June.

The following article that appeared in the 15 June 1943 issue of Naval Aviation News suggests implementation took time:

Unfortunately, it doesn't provide any dates for implementation and interestingly enough, omits mention of the F2A. It also does not include the SBD-5, which suggests that these were already equipped with shoulder harnesses at the factory; the first delivery was April 1943.

An article in the 1 January 1944 issue of Naval Aviation News suggests that shoulder harness implementation was still being driven at the local level (VC-19 was a composite squadron operating FM Wildcats and TBM Avengers off escort carriers in the north Atlantic by late 1943).

More information on shoulder harness implementation would be welcomed.

FJ-3 Canopy Details

It's hard to add much to Steve Ginter's excellent monograph on the FJ-3 (http://www.ginterbooks.com/NAVAL/NF88.htm) but while pictures of the area under the canopy are included, some modelers (well, at least one) have asked for more detail.

I was also surprised in researching the question to discover that the ADF antenna system changed between the early FJ-2 and the FJ-3. The early FJ-2 had the clear dome mounted aft of the armor plate and a sense antenna on the inner surface of the sliding canopy; the dome was replaced by a wire loop on the FJ-3 with no sense antenna on the canopy.

It's difficult to get a good image of the very fine wires of the sense antenna on the inside of the FJ-2 canopy.

 There is a picture of the FJ-3 antenna from page 190 of the Ginter monograph.

As for the rest of the hardware under the canopy aft of the headrest, note that there was a shear web between the sides of the canopy with a couple of items located on it.

The screw jack that opened the canopy was mounted on the fuselage deck below the shear web along with some other odds and ends. When the canopy was closed, the area was greatly simplified from a modeling standpoint.

The Late, Great Gordon Stevens

Gordon Stevens basically invented the vacuform kit. You can read about it HERE in his own words. We corresponded in the early 1980s (long before email) after I ordered a Douglas F3D Skyknight kit that he had advertised in Finescale Modeling. The result was that he binned his A3D Skywarrior masters that were essentially complete since, as he put it, "my A-3 was something of a caricature", and created replacements using Douglas drawings that I provided. I was very pleased to be of help to him and the resulting kit (except for the canopy, which has become discolored over time) is excellent. We lost touch thereafter when my career took precedence over my hobbies.

It was a happy day when I finally was able to buy one of his very rare Box-Kites XFT-1 kits, basically completing a 1/72-scale kit collection of U.S. Navy carrier airplanes.

I plan to build it eventually as part of a 1/72-scale model collection of U.S. Navy carrier airplanes. Some will be built from his Rareplane vacuform kits, which still match or better the accuracy of shape and detail of more recent injection models of the same type.

A few years ago, I referred to him as late and great in a post on a modeling website. I was very pleased to be corrected. I regret to report that the statement is now true. 

Grumman A-6C TRIM

1 November 2015: Added additional illustrations

TRIM is not a typo. Before TRAM (see http://tailspintopics.blogspot.com/2015/09/grumman-6a-vs-6e-intruder.html), there was TRIM (Trails, Roads, Interdiction Multisensor). It included a large belly-mounted pod that contained a Low-Light-Level Television (LLLTV) camera and a Forward-Looking Infrared (FLIR) camera. The LLLTV amplified images to make them more visible and the FLIR detected objects that were hotter than their surroundings.

The TRIM capability included Black Crow antennas in the radome to detect truck ignition systems and point the way to the source. It was an early attempt to detect, track, and attack vehicles operating at night along the Ho Chi Minh Trail in Vietnam.

Twelve A-6As, BuNos 155647, 648, 653, 660, 663, 667, 670, 674, 676, 681, 684, and 688, were modified to be A-6Cs. The installation of the pod required the addition of hard points on the bottom of the fuselage as well as cockpit and other minor hardware changes. They were all delivered in the first half of 1970.

Mick Roth recently provided me with additional documentation on the pod that answered some questions I had. This illustration is a work in progress.

 The following sketch shows the access panels and other details; it is missing the stiffeners/fences on the outboard side of the fins.

The turret was rotated aft to protect the clear panels when the LLLTV and FLIR were not in use.

(Note that the lower lip is broader than on my drawing.)

The windows were flat and not symmetric, with the narrower FLIR camera mounted in the right side of the turret looking through germanium composition glass and the LLLTV camera  in the left side looking through quartz composition glass.

The changes to the cockpit included the addition of unique mission equipment control panels and the substitution of a multi-purpose scope that could display FLIR, LLLTV, or the standard A-6A radar.

Part of my early confusion about the pod is that most of the good pictures available are of a prototype configuration.

The production pod had air outlets on the side of the turret section instead of an inlet, the bottom of the turret opening had an extended lip, and the afterbody was extended downward to the bottom of the fins except for the last foot or so.

Although the A-6C SAC shows the inboard wing fences inboard of the inboard pylon like the A-6E, they were actually outboard of the inboard pylon like the A-6A.

The A-6C was disappointing from a mission-effectiveness standpoint, not to mention heavy and slow due to the weight and drag of the pod. The landing weight required the substitution of an EA-6B tailhook and even then the A-6Cs was more restricted from a fuel standpoint for arrested landings than the A-6As. One A-6C was lost in an operational accident. The other 11 were eventually converted to A-6Es.

Modeling the Bell XFL-1 Airabonita

31 January 2023: Added a size comparison of the XFL-1 and P-39 empennages.

The Bell XFL-1 Airabonita was a one-off prototype based on Bell's P-39 that competed with the Vought XF4U-1 and the Grumman XF5F-1 following the U.S. Navy's 1938 carrier-based fighter competition.

It looks like it would be a colorful and straightforward conversion of the P-39, kits of which are available in every popular scale from 1/144 to 1/32. In fact, several have been done and documented in articles in modeling magazines. However, most—if not all—fall short of representing the actual XFL-1 configuration. Unfortunately, most of the structure, particularly the canopy, was different in detail from the P-39. Not even the 1/72 XFL-1 kits that are available are accurate, since they have the P-39 wing planform, which was somewhat different in taper and span.

(Note that the XFL-1 wing root is also closer to the fuselage centerline than the P-39's.)

 For example, this is what it takes to convert a P-39 wing to an XFL-1 wing:

The empennage (both initial and final) is also very different from the P-39's (the final horizontal stabilizer is about the same size and shape but the elevator itself has significantly more chord).

Another, more notable difference was the canopy and door, since over-the-nose visibility was critical for a carrier-based airplane.

All this and more is contained in my XFL-1 monograph, available from Steve Ginter:

http://www.ginterbooks.com/NAVAL/NF81.htm

In addition to most of the photographs extant of the XFL-1, there are illustrations of the configuration changes during development like the empennage. Since the Navy specifically included the XFL-1 in the competition to evaluate the performance benefit of the new 1,000-hp Allison liquid-cooled engine,  it includes a summary of the history of aero-engine development, comparing and contrasting the benefits and shortcomings of the liquid-cooled versus air-cooled engine. It also places the XFL-1 in the context of the Navy's rapid transition to monoplanes and new requirements like armor and self-sealing fuel tanks.

Even if you don't need a model of an XFL-1, the monograph provides interesting background on aero engine and Navy airplane development between the World Wars.

Grumman A-6A vs A-6E Intruder

30 January 2016: Corrections from Mick Roth and updated External Differences table

20 September 2015: Added detail provided by Mick Roth.

16 September 2015: Numerous changes have been incorporated over the past few days: Steve Belanger (see http://www.aoadecals.com/) Richard Brumm (also see his comment below) and others have provided additional information. 

A model builder sometimes asks for the differences between the A-6A and the A-6E. There isn’t a simple answer. Initially, the major changes were avionics and other internal items, with the only notable external change being the ECM antennas—and that wasn't true for the first 20 or so A-6Es—and possibly the location of the inboard wing fence. Note also that over 200 As were rebuilt as Es, making Bureau Numbers unreliable as a differentiator. (The first production A-6E was 158041.)

The Bible for the A-6 is Intruder: The Operational History of Grumman’s A-6 by Mark and Rick Morgan, published by Schiffer.  The subtitle doesn't do it justice because it also covers development, configuration changes, and in-service problems.

  Also see http://thanlont.blogspot.com/2012/12/grumman-6-intruder-history.html

Rick generously provided content and illustrations for this post but he only reviewed a first draft of the text so any errors and omissions are all mine.

The external changes can be simplified into the following categories:

Early As

Later As

Early Es

CAINS

TRAM

SWIP/Composite Wing

Note that I have arbitrarily differentiated Early and Late A-6As as circa 1970 after the incorporation of improved defensive systems in this summary.

Also see Brumm comment below.

Due to problems encountered in flight test and Navy evaluation, wingtip-mounted speed brakes were added at BuNo 149940 and the perforated fuselage-mounted speed brakes were deactivated shortly after the first A-6As were delivered to operational squadrons. The fuselage speed brake assembly was deleted entirely in production at BuNo 154170 and replaced with a blank panel. However, earlier A-6s, including those subsequently converted to A-6Es, retained the original perforated structure covering the speed brake well until it had to be replaced for cracking or corrosion. More than 10 were still flying with the original panel in 1991 while deployed for Operation Desert Storm. This is an example of a former A-6A in June 1983.

 Rick Morgan Photo

Early As had fairings attached to the forward portion of the tailhook and early Defensive Electronic Countermeasures (DECM) equipment and the ALE-18 chaff dispenser.

 The ALE-18 dispensed packets of chaff through a small slot on the lower left-hand side of the fuselage between the engine exhaust and the speed brake well. It was the production standard between production number 19 and 433.

 Small ALR-15 Radar Warning Receivers were mounted on the wingtips between the position lights on A-6A production number 19 through 358.

New and improved defensive systems were added as a result of combat experience, on the fly so to speak, which resulted in the Later A configuration. For example, two ALE-29A dispensers were added aft of a truncated Doppler radar antenna fairing beginning in either March 1969 and at production number 434 (Roth) or February 1970, replacing the ALE-18. These contained separate cartridges of either chaff or a flare with 30 tubes per dispenser.

The Later A-6A DECM antennas were boom mounted on the outboard pylon and under the leading edge of the wingtip:

Steve Belanger noted that the boom mounted antenna (AN/ALQ-100) was an airframe change dated 29 February 1968; the wingtip receivers (AN/APR-25), 30 April 1968. Mick Roth reported that the ALQ-100 was added at production number 310 and the APR-25 replaced the ALR-15 at production number 359. However, retrofit might have taken some time although A-6s that were in combat would get them as soon as possible during deployment. It's rare to see an A-6A that has one antenna and not the other but VMA (AW)-533 had only the wingtip receivers circa 1968/1969 on their 1541XX A-6As even though the addition of the ALQ-100 was the earlier change. This is an example:

John Murphy via Steve Belanger

Externally and from a modeler's perspective of the cockpit, the first 72 Es were basically the same as Later As except for ECM antennas (and even then the first A-6Es were delivered with the Later A-6A DECM antennas), the substitution of the GRU-7 seat (also retrofitted to some As) for the GRU-5 and possibly the location of the inboard wing fence.

Early A-6A Cockpit (gunsight protective cover in place):

Later A-6A Cockpit (note the addition of a radar warning display on the instrument panel above the center console):

 Scanned from the VMA(AW)-533 1972-1973 Cruise Book by Steve Belanger

The A-6E cockpit was initially similar to the Later A-6A's except for the GRU-7 ejection seat.

The ejection seats:

Production A-6Es #16 and 18 were delivered to VA-65 with A-6A DECM antennas.

The A-6A ECM antenna on the outboard pylon was subsequently replaced on A-6Es with three in a large fairing on the inboard-wing leading-edge. It had a recess in it for the main landing gear door.

The inboard portion of the A-6A's stall strip on the leading edge, shown here, was retained.

This change to the A-6E inboard leading edge resulted in the inboard wing fence being relocated slightly inboard. On the A-6A (and A-6C contrary to its SAC drawing), it was located slightly but notably outboard of the inboard pylon. On the A-6E, it was moved to be slightly but still clearly inboard of the inboard pylon. Click HERE for the relative locations.

Note that after the first few deployments, the black radomes were replaced with tan ones (the natural color of the fiberglass) to reduce conspicuity. Grey and white paints were subsequently approved that did not affect transitivity.

The inlets and vents on the right shoulder panel were different:

CAINS (Carrier Airborne Inertial Navigation System) was the replacement for the original INS that was one of the avionics carryovers from the A. It resulted in the addition of a large external air scoop on the upper aft fuselage and a small exhaust on the lower left aft fuselage (the original inlet at the base of the vertical fin was blanked off). In production, CAINS preceded the installation of TRAM (Target Recognition Attack Multisensor) turrets but all production A-6s delivered with CAINS had provisions for TRAM, including a removable panel at the bottom of the radome and the relocation of the anticollision light from the nose landing gear door to a light under each engine nacelles (two were doubtless required to meet the minimum viewing angles). The TACAN antenna was relocated to the underside of the left engine nacelle.

Note that the first A-6As had the angle of attack indexer lights evenly spaced along the side of the door and no TACAN antenna on it.

Since CAINS preceded TRAM, all A-6s with the sensor turret under the forward fuselage had the large inlet scoop, but not all A-6s with the large inlet scoop had the turret. However, the latter configuration would be relatively rare although it could occur simply due to a requirement for turret repair with no spare available. This is a former A-6A with the CAINS air scoop but no turret.

TRAM, which provided FLIR (Forward Looking Infra Red) among other things, resulted in a notable change on both sides of the cockpit.

 Note that there is one screen instead of two for the pilot and vice versa on the right side.

As in the earlier A-6s, when in use the bombardier's scopes were covered by a hood to maximize readability.

SWIP (Systems/Weapon Improvement Program) was a package of avionics changes and a new, all-composite wing that would extend the A-6’s service life. Because of delays in the wing’s design and development, some aircraft received some of the SWIP changes before than the wing. The only external SWIP change feature might be the addition of an aft-facing DECM antenna mounted above the fuel dump on the composite wing and possibly on the metal wing. Note that formation ("slime") lights were added to the wingtip (and the fuselage as shown above), possibly in production with BuNo 161092, but beginning in October 1982 in any event.

The composite wing configuration is covered in detail here: http://tailspintopics.blogspot.com/2014/01/grumman-6-wing-fold-differences.html

The later formation lights replaced much smaller rectangular orange lights on the fuselage.

 Note that this A-6E is a former A-6A that has the CAINS air scoop, the perforated panel over the speed brake well, and a panel on the underside of the nose in lieu of the TRAM turret (see http://www.usscoralsea.net/images/cv4319800425FD3RL.jpg). The picture is easy to date as taken in April 1980 since this is one of the airplanes with ID markings added for the Tehran hostage rescue mission.

The SWIP  improvements were supposed to include a head-up display for the pilot but this doesn't seem to have been realized before the A-6s were prematurely put out to pasture.